The default interface of Symmetry/Double Attach is illustrated in Figure 6.1.39(a). The user can select any function in Double Attach to display the interface as shown in Figure 6.1.39(b). In Symmetry function, there are three types of part geometry for the user to input: NO SYMMETRY, SYMMETRY and HALF SYMMETRY INPUT. In Double Attach function, there are three types of part geometry for the user to select: LEFT / RIGHT HALF INPUT, LEFT / RIGHT FULL INPUT and TWO PARTS.
(a) (b)
Figure 6.1.39 Symmetry/Double Attach
This function allows the user to define a symmetrical die by mirroring a half symmetry plane.
Three part geometry options are available in the SYMMETRY dialog box. There are described as following:
NO SYMMETRY (Default)
This is the default option. All other functions provided in the SYSMMETRY dialog box are disabled.
SYMMETRY
The part is defined as symmetrical (the part itself is usually symmetrical).
HALF SYMMETRY
INPUT
Only one half of the part geometry is available. The function will mirror the other half of the part about a symmetry plane to create a complete part.
There are three types of symmetry options available. There are described as the following:
X-Z PLANE
The symmetry plane is parallel to the XZ plane of the Global Coordinate System. The user must select two points to define the XZ plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.
Y-Z PLANE
The symmetry plane is parallel to the YZ plane of the Global Coordinate System. The user must select two points to define the YZ plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.
TWO-XY-POINT
The symmetry plane is normal to the XY plane of the Global Coordinate System. The user must select two points to define the XY plane. The first point is used to define the location of the symmetry plane, while the second point is used to define direction of the axis of symmetry.
The user can enter the SHIFT value and
click on or
to move
the symmetry axis. If the nodes at the plane of symmetry are not collinear
along the symmetry plane, the ALIGN NODES function can be utilized to correct
the problem. When the part is defined as Half Symmetry, eta/DYNAFORM will
activate the ALIGN NODES function. The user can define the tolerance
input field to align the nodes along the line of symmetry. After clicking
on this button, the program will pop up a DYNAFORM Question dialog box, as
shown in Figure 6.1.40, and highlight the result from the operation. As
illustrated in Figure 6.1.41, the user can select YES to accept the result or
select NO to correct the inconsistency between some nodes on symmetry plane and
symmetry plane direction within the offset range via adding align nodes by
cursor. The user can also select ABORT to redefine the offset range.
Figure 6.1.40 DYNAFORM Question dialog box
Figure 6.1.41 Highlight nodes
NOTE: If the symmetry plane is not defined to be die, when clicking on ALIGN NODES, the message window prompts:
DIE NOT DEFINED IN DATABASE
If HALF SYMMETRY INPUT is selected, the MIRROR GEOMETRY button will be activated. This function allows the user to select elements which will be mirrored about the symmetry plane(s). The UNDO button is used to undo the mirror operation.
The steps needed to define a symmetrical die are listed as the following:
1. Read in the symmetrical geometry, mesh it and assign it as DIE.
2. Select a geometry type, for example, HALF SYMMETRY.
3. Select a symmetry type, for example, X-Z PLANE.
4. Using the SELECT POINT button to select two points to define the symmetry plane and the axis direction.
Figure 6.1.42 Half Symmetry Part with X-Z Plane
5. Click on the MIRROR GEOMETRY SYMMETRY button, following by selecting the part as illustrated in Figure 6.1.42. The mirror result is illustrated in Figure 6.1.43.
Figure 6.1.43 The Mirroring Result
This function allows the user to design Double Attach by entering the part geometry. There are three types of part geometry listed below.
LEFT / RIGHT
HALF INPUT
This function allows the user to input one part geometry, then mirror another same part by using Symmetry function. Once this button is selected, the Symmetry interface is activated, as shown in Figure 6.1.44.
Figure 6.1.44 Left/Right Half Input
After double attach is defined, SHOW button is enabled to highlight the left half or the right half.
LEFT / RIGHT FULL
INPUT
This function allows the user to input two part geometries with the same outlines and different interior. These two outlines must be in the symmetrical position without overlap in order for the function to work. Once this button is selected, the Symmetry Type is disabled, but Select buttons for Left and Right are activated, as shown in Figure 6.1.45.
Figure 6.1.45 Left/Right Full Input
After double attach is defined, the parts of the left half (or the right half) are automatically added to LEFT PART (or RIGHT PART) list.
TWO PARTS
This function allows the user to input two totally different part geometries. Once this button is selected, the Symmetry Type is disabled, but Select buttons for Left and Right are activated. The interface is similar to the one in Figure 6.1.45.